1. Field of the Invention
The present invention relates to an improved technique for driving matrix displays, and in particular, passive matrix displays including row and column configurations of electro-optical display elements (e.g., liquid crystal, LED, plasma, and Electroluminescent).
2. Discussion of the Background
Matrix displays are addressed by coincident selection of a pixel (picture element) at the intersection of a given row and column. Multiplexing is the term applied to the time division whereby the pixels are excited or driven. Problems arise when driving large matrix displays (e.g., a TV display). With a large display, if the electro-optical display elements are electrically linear, crosstalk (noise in the form of unwanted excitation of unselected pixels) limits the size of the display. If the display elements are non-linear, such as in displays that use a thin film transistor (TFT) switch at the intersection of every row and column, then there are few matrix driving problems caused by crosstalk. However, distributed TFT devices are expensive, and the cost escalates exponentially with the size of the display.
Various techniques have been devised for extending the size of the matrix of linear display elements it is feasible to drive. A tutorial is found in HANDBOOK OF LIQUID CRYSTAL RESEARCH, Chapter 11, Addressing of Passive Matrix, RMS Responding Liquid Crystal Displays, by Terry Scheffer, pp. 445-471; Edited by: Collings and Patel, Oxford University Press, 1997 (hereinafter Scheffer). The contents of the "HANDBOOK OF LIQUID CRYSTAL RESEARCH" are incorporated herein by reference. This tutorial incorporates 40 references.
U.S. Pat. No. 4,586,039 discloses a method of frame frequency adjustment in response to a voltage detection. The adjustment is made after addressing, involves no storage of illumination data and applies only to AMLCDs, not passive displays.
Likewise, U.S. Pat. No. 4,383,039 describes a method of interaction by the user to access data locations on the display. This patent does not address the efficiency or effectiveness of display addressing.
U.S. Pat. No. 5,508,716 illustrates row pair addressing using randomly changing pairs of rows to rely on some sort of statistical cover-up of the defective pixels in the pairs. The benefits of faster response, higher contrast and a wider viewing angle would accrue to the method of the present invention that selects row-pairs to minimize pixel defects. It does not disclose storage and analysis of the data for row-pairs prior to delayed excitation.